As an angular velocity detection apparatus, oscillation type angular velocity detection apparatuses of various shapes, such as a tuning bar type and tuning fork type, have been proposed and practically used. For example, a tuning fork type angular velocity detection apparatus has a high Q-value, and thus, stable oscillation and high sensitivity can be obtained.
There has been proposed a tuning fork type angular velocity detection apparatus in which a driving electrode to which a driving voltage for oscillating an arm (oscillator) is applied and a detection electrode that outputs a detection signal according to an angular velocity applied to the arm are formed on the same arm.
In the angular velocity detection apparatus described above, if an oscillation direction of the arm is a horizontal direction, a detection direction is a vertical direction; and in a state where an angular velocity is not applied to the arm, a detection signal is not outputted from the detection electrode. Further, when an angular velocity is applied to the arm while the arm oscillates in the horizontal direction, the arm also oscillates in the vertical direction by Coriolis force, and the angular velocity is detected based on the oscillation in the vertical direction.
Meanwhile, a piezoelectric thin film structure applied to the oscillator of a conventional angular velocity detection apparatus includes a three-layer structure consisting of an oxide layer (SiO2 layer), a platinum (Pt) layer disposed on the SiO2 layer, and a lead zirconate titanate (PZT: Pb(ZrX, Ti1-X)O3) layer disposed on the Pt layer. The SiO2 layer serves as a layer for preventing the diffusion of Pb from the PZT layer.
However, in the above piezoelectric thin film structure applied to the oscillator of a conventional angular velocity detection apparatus, a lead (Pb) component in the PZT may be diffused into a substrate in a firing process during film formation, and the piezoelectric performance may deteriorate. Thus, the sensitivity of a sensor of the angular velocity detection apparatus may also deteriorate.